ASTM F3374-19

Standard Guide for Active Fixation Durability of Endovascular Prostheses

SIGNIFICANCE AND USE
5.1 Once implanted, active fixation systems are subjected to cyclic loading that can be caused by blood flow, musculoskeletal motion, and other sources. The focus of this document is on axial loading caused by hemodynamics. However, depending on the device design other loading modes could influence AFC or attachment mechanism durability (e.g., radial dilatation could lead to longitudinal foreshortening and axial loading on an active fixation system). Damage to AFCs and/or attachment mechanisms may not necessarily lead to device malfunction, but could cause embolization of portions of the device, device migration, endoleaks, or other patient complications (1-4).4 Therefore, durability testing of AFCs and attachment mechanisms is important to ensure that these components are capable of maintaining structural integrity for a defined lifetime.  
5.1.1 A test method developed following this standard guide can be used to determine the durability of AFCs and/or attachment mechanisms under the desired loading which can be used to assess conformance to product specifications, consensus standards, and guidance documents as well as to support regulatory submissions, quality control, and manufacturing.  
5.2 This guide provides examples and recommendations so that users can develop an appropriate active fixation durability test for their device design that mechanically challenges either the AFC, the attachment mechanism, or both simultaneously. It should be recognized that both AFCs and attachment mechanisms need to be evaluated to fully characterize active fixation system durability for design verification testing. While testing of the entire active fixation system may typically be preferable, this guide recognizes that there might be situations where this is not practical or desired and allows for independent testing of AFCs and attachment mechanisms. This guide does not contain an exhaustive list of test methods for active fixation durability and methods not included herei...
SCOPE
1.1 This guide addresses how to conduct in vitro durability testing on active fixation components (AFCs) and attachment mechanisms of endovascular prostheses. It does not address the durability of fixation systems that reside solely within the vessel lumen to resist device migration (e.g, radial force and friction, adhesives, or geometric fit).  
1.2 This guide was developed to address active fixation durability for aortic stent grafts. It is not intended to address fixation durability for other endovascular prostheses such as inferior vena cava filters, transcatheter heart valves, barbed venous stents, ancillary fixation devices (e.g, staples or adhesives), or cardiac devices (e.g., left atrial appendage device or mitral repair device). However, some of the techniques and guidance within may be applicable to the in vitro testing of those other devices.  
1.3 This guide does not directly apply to implants with absorbable AFCs although many aspects of this standard are applicable to those products.  
1.4 This guide does not provide the in vivo physiologic loading conditions for endovascular prostheses. It is the responsibility of the user to determine the loading or deformation conditions for their particular device and indication. Typically, an axial loading (force or displacement) mode caused by hemodynamics is used, although other modes are possible and should be considered.  
1.5 This guide does not recommend any specific test method or apparatus for evaluating active fixation durability. It is recognized that there are multiple valid ways to conduct active fixation durability testing and as such this guide provides general recommendations and topics to consider so that users can successfully develop a test plan for their device.  
1.6 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.7 This standard does not purport to address al...

General Information

• Status: Published
• Publication Date: 31-May-2019
• ICS: 11.040.40 - Implants for surgery, prosthetics and orthotics
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.30 - Cardiovascular Standards

Relations

• Refers: ASTM F3211-17 - Standard Guide for Fatigue-to-Fracture (FtF) Methodology for Cardiovascular Medical Devices
• Effective Date: 01-Sep-2017
• Refers: ASTM F2942-13 - Standard Guide for <emph type="bdit">in vitro</emph> Axial, Bending, and Torsional Durability Testing of Vascular Stents
• Effective Date: 15-Aug-2013
• Refers: ASTM F2477-07(2013) - Standard Test Methods for <emph type="bdit">in vitro</emph> Pulsatile Durability Testing of Vascular Stents
• Effective Date: 01-Mar-2013
• Refers: ASTM E739-10 - Standard Practice for Statistical Analysis of Linear or Linearized Stress-Life (<bdit>S-N</bdit>) and Strain-Life (<bdit>&#949;-N</bdit>) Fatigue Data
• Effective Date: 01-Nov-2010
• Refers: ASTM F2477-07 - Standard Test Methods for <i>in vitro</i> Pulsatile Durability Testing of Vascular Stents
• Effective Date: 01-Apr-2007
• Refers: ASTM F2477-06 - Standard Test Methods for <bdit>in vitro</bdit> Pulsatile Durability Testing of Vascular Stents
• Effective Date: 01-Nov-2006
• Refers: ASTM E739-91(2004)e1 - Standard Practice for Statistical Analysis of Linear or Linearized Stress-Life (<bdit>S-N</bdit>) and Strain-Life (<bdit>&#949;-N</bdit>) Fatigue Data
• Effective Date: 01-May-2006
• Refers: ASTM E739-91(2004) - Standard Practice for Statistical Analysis of Linear or Linearized Stress-Life (<i>S-N</i>) and Strain-Life (&#949;-<i>N</i>) Fatigue Data
• Effective Date: 01-May-2004
• Refers: ASTM E739-91(1998) - Standard Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (e-N) Fatigue Data
• Effective Date: 10-Apr-1998
• Referred By: ASTM F3036-21 - Standard Guide for Testing Absorbable Stents
• Effective Date: 01-Jun-2019

Overview

ASTM F3374-19: Standard Guide for Active Fixation Durability of Endovascular Prostheses provides a comprehensive framework for the in vitro durability testing of active fixation components (AFCs) and attachment mechanisms in endovascular prostheses, with a primary focus on aortic stent grafts. The guide addresses the significance of cyclic mechanical loading, especially axial loading caused by hemodynamics, and underscores the importance of ensuring the long-term structural integrity of active fixation systems to prevent device migration, embolization, endoleaks, and other patient complications. While primarily intended for aortic stent grafts, certain techniques and recommendations within this standard may help inform testing of other device types.

Key Topics

• Durability Testing Focus: The standard covers best practices for in vitro mechanical testing of AFCs and attachment mechanisms, considering cyclic loading scenarios that replicate blood flow and musculoskeletal motion.
• Types of Loading: Emphasis is placed on axial loading, but the standard recommends considering other relevant loading modes such as radial or torsional stresses depending on device design and clinical context.
• Test Methods and Apparatus: ASTM F3374-19 does not prescribe a specific test method or apparatus. Instead, it provides general recommendations and considerations for developing test plans specific to a manufacturer’s device and intended clinical use.
• Test Specimens: The guide suggests testing finished devices, components, or surrogate samples that represent the actual clinical product. Justification for sample size and configuration is vital.
• Mock Vessels and Fixtures: Recommendations are provided for using mock vessels and/or rigid fixtures to replicate physiological conditions, emphasizing the need for appropriate material selection, temperature control, and solution environment.
• Loading Determination: Determining realistic test loads should be based on physiological data, computational modeling, and risk-based analysis. Special attention is required for worst-case loading scenarios.
• Evaluation and Inspection: Continued monitoring and inspections before, during, and after testing are necessary to detect damage such as AFC fracture, attachment mechanism failure, or device displacement.

Applications

• Device Design Verification: Manufacturers use ASTM F3374-19 to verify the durability of active fixation systems in endovascular prostheses during the design phase, ensuring devices can withstand anticipated physiological loads over their expected lifetime.
• Regulatory Submissions and Quality Control: Durability data generated from testing following this guide supports regulatory submissions and ongoing quality assurance processes, demonstrating conformance to product specifications and international consensus standards.
• Manufacturing Assessments: Testing performed according to ASTM F3374-19 helps manufacturers evaluate consistency in production processes and the impact of design or material modifications on fixation durability.
• Customization of Test Protocols: Since the standard provides a flexible framework rather than prescriptive test methods, it allows user adaptation based on unique device configurations, expected anatomical conditions, and intended clinical indications.

Related Standards

ASTM F3374-19 references or complements several other recognized standards and documents, including:

• ASTM F2477: Test methods for in vitro pulsatile durability testing of vascular stents.
• ASTM F2942: Guide for in vitro axial, bending, and torsional durability testing of vascular stents.
• ASTM F3172: Guide for device size and sample size selection for endovascular devices.
• ASTM F3211: Guide for fatigue-to-fracture methodology for cardiovascular medical devices.
• ISO 25539: Cardiovascular implants – Endovascular devices.
• ASME V&V40: Assessing credibility of computational modeling and simulation results for medical devices.

Practical Value

By following ASTM F3374-19, device manufacturers and testing laboratories can:

• Enhance patient safety by ensuring endovascular prostheses are rigorously tested for long-term mechanical durability.
• Mitigate risks related to device migration, detachment, or structural failure.
• Support international regulatory compliance and acceptance of durability test results.
• Standardize testing approaches, facilitating consistency and comparability across different device development projects.

Keywords: active fixation component, endovascular prosthesis, durability testing, aortic stent grafts, attachment mechanism, cyclic loading, mechanical testing, device migration prevention, regulatory compliance.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3374 − 19
Standard Guide for
Active Fixation Durability of Endovascular Prostheses
This standard is issued under the fixed designation F3374; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This guide addresses how to conduct in vitro durability
responsibility of the user of this standard to establish appro-
testing on active fixation components (AFCs) and attachment
priate safety, health, and environmental practices and deter-
mechanismsofendovascularprostheses.Itdoesnotaddressthe
mine the applicability of regulatory limitations prior to use.
durability of fixation systems that reside solely within the
1.8 This international standard was developed in accor-
vessel lumen to resist device migration (e.g, radial force and
dance with internationally recognized principles on standard-
friction, adhesives, or geometric fit).
ization established in the Decision on Principles for the
1.2 This guide was developed to address active fixation
Development of International Standards, Guides and Recom-
durability for aortic stent grafts. It is not intended to address mendations issued by the World Trade Organization Technical
fixation durability for other endovascular prostheses such as
Barriers to Trade (TBT) Committee.
inferior vena cava filters, transcatheter heart valves, barbed
venous stents, ancillary fixation devices (e.g, staples or
2. Referenced Documents
adhesives), or cardiac devices (e.g., left atrial appendage
2.1 ASTM Standards:
device or mitral repair device). However, some of the tech-
E739 PracticeforStatisticalAnalysisofLinearorLinearized
niques and guidance within may be applicable to the in vitro
Stress-Life (S-N) and Strain-Life (ε-N) Fatigue Data
testing of those other devices.
F2477 Test Methods forin vitro Pulsatile Durability Testing
of Vascular Stents
1.3 This guide does not directly apply to implants with
absorbable AFCs although many aspects of this standard are F2942 Guide forin vitro Axial, Bending, and Torsional
Durability Testing of Vascular Stents
applicable to those products.
F3172 Guide for Design Verification Device Size and
1.4 This guide does not provide the in vivo physiologic
Sample Size Selection for Endovascular Devices
loading conditions for endovascular prostheses. It is the re-
F3211 Guide for Fatigue-to-Fracture (FtF) Methodology for
sponsibilityoftheusertodeterminetheloadingordeformation
Cardiovascular Medical Devices
conditions for their particular device and indication. Typically,
2.2 Other Documents:
an axial loading (force or displacement) mode caused by
ASMEV&V40 Assessing Credibility of Computational
hemodynamics is used, although other modes are possible and
Modeling and Simulation Results throughVerification and
should be considered.
Validation: Application to Medical Devices
1.5 Thisguidedoesnotrecommendanyspecifictestmethod
ISO 25539 Cardiovascular implants – Endovascular devices
or apparatus for evaluating active fixation durability. It is
– Part 1: Endovascular prostheses
recognized that there are multiple valid ways to conduct active
fixation durability testing and as such this guide provides
3. Terminology
general recommendations and topics to consider so that users
3.1 Definitions:
can successfully develop a test plan for their device.
3.1.1 endovascular prosthesis, n—vascular prosthesis (in-
1.6 Units—The values stated in SI units are to be regarded
cluding modular components) which resides partially or com-
as standard. No other units of measurement are included in this
pletely within a blood vessel, or vascular conduit to form an
standard.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This guide is under the jurisdiction of ASTM Committee F04 on Medical and contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Surgical Materials and Devices and is the direct responsibility of Subcommittee Standards volume information, refer to the standard’s Document Summary page on
F04.30 on Cardiovascular Standards. the ASTM website.
Current edition approved June 1, 2019. Published July 2019. DOI: 10.1520/ Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
F3374-19. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3374 − 19
internal bypass or shunt between sections of the vascular malfunction, but could cause embolization of portions of the
system, delivered and deployed using a delivery system [from device, device migration, endoleaks, or other patient compli-
ISO 25539-1]. cations (1-4). Therefore, durability testing of AFCs and
attachment mechanisms is important to ensure that these
3.2 Definitions of Terms Specific to This Standard:
components are capable of maintaining structural integrity for
3.2.1 active fixation component (AFC), n—the portion or
a defined lifetime.
sub-assembly of an endovascular prosthesis active fixation
5.1.1 Atestmethoddevelopedfollowingthisstandardguide
system (e.g., anchor, hook, barb of a suprarenal stent) designed
can be used to determine the durability of AFCs and/or
to provide axial fixation which prevents device migration;
attachment mechanisms under the desired loading which can
these components pierce the native vascular tissue to provide
be used to assess conformance to product specifications,
fixation.
consensus standards, and guidance documents as well as to
3.2.2 active fixation system, n—system or feature of the
support regulatory submissions, quality control, and manufac-
endovascular prosthesis that is comprised of active fixation
turing.
components and attachment mechanisms and which is de-
5.2 This guide provides examples and recommendations so
signed to prevent migration by embedding beyond the luminal
that users can develop an appropriate active fixation durability
surface of the vessel and by attachment to or integration with
test for their device design that mechanically challenges either
the endovascular prosthesis.
theAFC, the attachment mechanism, or both simultaneously. It
3.2.3 attachment mechanism, n—the connection(s) and/or
should be recognized that both AFCs and attachment mecha-
structure(s) linking the AFC to the remainder of the endovas-
nisms need to be evaluated to fully characterize active fixation
cular prosthesis (e.g., connection of a barb to a stent via
system durability for design verification testing. While testing
welding, suture or other bonding mechanism; suprarenal stent;
of the entire active fixation system may typically be preferable,
or sutures connecting a proximal stent to graft material).
this guide recognizes that there might be situations where this
3.2.4 load, n—used to denote continuous and time-varying
is not practical or desired and allows for independent testing of
forces, stresses, strains, torques, deflections, twists or other
AFCsandattachmentmechanisms.Thisguidedoesnotcontain
parameters that describe the applied fatigue stimuli. Typically
an exhaustive list of test methods for active fixation durability
these fatigue stimuli are described by a mean value and an
and methods not included herein may be acceptable for
alternating value.
evaluating active fixation durability. Furthermore, this guide
does not include information on how to handle all patient
3.2.5 mock vessel, n—a simulated blood vessel typically
manufactured from an elastomeric material. complexities such as calcium deposits or weakened aortic
tissue. For assistance regarding super-physiological testing, the
4. Summary of Test Guides user is referred to ASTM F3211.
5.2.1 The success of an active fixation durability test
4.1 This guide covers in vitro durability testing of active
method depends on the ability of the test apparatus to consis-
fixation components (AFCs) and attachment mechanisms.
tentlyinducethedesiredloading(forceand/ordisplacement)to
Duringdevelopmentofanendovascularprosthesis,itiscritical
the test specimen at the applied test frequency for the entire
to test theAFCs and the attachment mechanisms because both
duration of the test.
are important to ensure active fixation system durability.
5.3 For most devices, active fixation durability testing will
4.2 Depending on the test objectives, it may be preferable to
need to be complemented by other types of durability testing
test the durability of the AFCs and attachment mechanisms
such as pulsatile, axial, bending, or torsional. ASTM F2477
separately or simultaneously. Example fixturing for these three
addresses pulsatile durability testing, ASTM F2942 addresses
potential testing modes are presented in Appendix X1.
axial, bending, and torsional durability testing, and ISO
4.3 Determining the appropriate loading on theAFC and/or
25539-1, in part, addresses general in vitro testing and dura-
attachment mechanism is critical and may be determined by
bility testing of endovascular prostheses.
analyticalforcebalance,computationalmodeling,clinicaldata,
flow studies, or other means. Care should be taken to ensure 6. Specimen Size, Configuration, and Preparation
that observed forces and/or motions are representative of the
6.1 Test Specimens—Test specimens should be finished
intended test conditions and do not introduce test artifacts.
devices, appropriate components, coupons extracted from the
device or component, or surrogate samples. Unless otherwise
5. Significance and Use
justified, test specimens should be representative of actual
clinical devices or components made by the final manufactur-
5.1 Once implanted, active fixation systems are subjected to
ing process, including sterilization. When deciding whether to
cyclic loading that can be caused by blood flow, musculoskel-
test whole devices or portions of whole devices, it is important
etal motion, and other sources. The focus of this document is
toconsiderthepossibilityoftestartifactsfromnon-physiologic
on axial loading caused by hemodynamics. However, depend-
loading. Testing of full devices or the largest practical subas-
ing on the device design other loading modes could influence
sembly may help reveal unforeseen failure modes as well as
AFC or attachment mechanism durability (e.g., radial dilata-
tion could lead to longitudinal foreshortening and axial loading
on an active fixation system). Damage to AFCs and/or attach-
The boldface numbers in parentheses refer to the list of references at the end of
ment mechanisms may not necessarily lead to device this standard.
F3374 − 19
characterize known failure modes. Because of the importance 7.3 Temperature Control System—The apparatus should in-
of the test specimen configuration (full device, surrogate clude a calibrated temperature control and measurement sys-
sample, etc.), justification should be provided for its selection. tem to maintain the temperature of the test specimen at 37 6
2°C unless otherwise justified.
6.2 Specimen Conditioning—Unless otherwise justified, test
7.4 Inspection Equipment—As appropriate to the test, a
specimens should be assembled with their delivery system and
means of periodically inspecting the test specimen for damage
trackedthroughsimulatedanatomyatphysiologictemperature,
during testing or during pauses in testing should be available.
using applicable accessories (if appropriate), prior to placing
This could include an optical microscope, x-ray, load
the test specimen in the test fixture or mock vessel. If the test
monitoring, resistance/conductivity measurements, visual in-
specimen and/or delivery system design does not permit
spection with a strobe light, borescope, ultrasonic
assembly of the test specimen and the delivery system, the
measurements, or other system capable of observing damage
device assembly and tracking processes should be physically
such as AFC fracture, suture breakage, etc.
simulated. Given the unique fixturing needed for loading the
test specimen, deployment through a simulated anatomy may
8. General Test Parameters
not be possible.
8.1 Determination of Loading—AFC and attachment
6.3 Selecting a Test Specimen Size—Endovascular prosthe-
mechanism loading in vivo is a function of the physiologic
sesaretypicallymanufacturedinseveralsizestoaccommodate
environment and the deployment orientation of the device.
different patient anatomies. Because in vivo loading and device
Selection of appropriate challenging loading conditions should
design (e.g., number of AFCs) can differ among device sizes,
include consideration of loading magnitude, angulation, test
justification should be provided when selecting which size test
specimen configuration, and other characteristics as described
specimen to evaluate. This justification should be based on
below.
which AFC and/or attachment mechanism experiences the
8.1.1 TheloadingontheAFCand/orattachmentmechanism
worst-case loading (the loading most likely to cause the most
should be based on a severe physiological environment in the
severe damage and/or failure) and may include analytical force
expected patient population (e.g., blood pressure and/or fluid
balance,computationalmodeling,clinicaldata,flowstudies,or
flow) or other justified condition (e.g., super-physiologic load-
other means.
ing in fatigue-to-fracture or replicating known clinical failure
6.3.1 Loading should be based on the loading experienced
loads). It may be appropriate to consider whether the loads
by AFCs and/or attachment mechanisms. This will depend on
applied to the active fixation system are diminished by passive
the number ofAFCs and/or attachment mechanisms per device
elements (e.g., friction between the vessel wall and the
size, on the active fixation system design (e.g., if the AFC
endovascular prosthesis resulting from chronic outward force).
design varies with device size), as well as on anatomical and
AFC and attachment mechanism loading can be determined by
activity level variations within the intended patient population.
analyticalforcebalance,computationalmodeling,clinicaldata,
6.4 Selecting a Number of Test Specimens—The number of
flow studies, or other means.An example of how to conduct an
test specimens selected should be justified and sufficient to analytical force balance is provided in Liffman et al. (5).
support any conclusions made based on the results. Although
References (5-11) provide examples of loading determination
not directly applicable, ASTM F3172 and ASTM E739 might in the abdominal aorta and References (12) and (13) provide
be useful in determining an appropriate number of test speci-
examples of loading determination in the thoracic aorta. If
mens.ASTM F3172, in particular, provides a statistical frame- computational modeling is used to determine loading, verifi-
work which incorporates risk into the sample size determina-
cation and validation activities should be conducted to assess
tion. Depending on how the user decides to conduct their the credibility of the computational model. ASMEV&V40
testing, a test specimen could be a singleAFC or a device with
provides a risk-based framework for determining the credibil-
multiple AFCs and attachment mechanisms; this will have a ity of computational models used in the development of
large impact on the number of test specimens needed. The
medical devices.
number of test specimens needed will depend on whether a test
8.1.2 The possibility of in vivo asymmetric deployment,
to success or a fatigue-to-fracture strategy is utilized. For
incomplete AFC engagement into vessel wall, and vessel
assistance on creating a fatigue-to-fracture test plan, please
angulation should be taken into account when determining
reference ASTM F3211.
loading. In determining the expected loads, it is important to
consider the interaction of the active fixation system with the
7. General Apparatus Requirements
native tissue as well as variation in physiological geometry,
tissue properties, and loads based on the expected patient
7.1 Measurement Devices—Devices such as linear variable
population. The relative direction of the loading input with
displacementtransducers(LVDTs),lasers,high-speedcameras,
respect to the active fixation system as well as input distribu-
and load transducers should be calibrated.
tionsamongandalongAFCsshouldalsobetakenintoaccount.
7.2 Cycle Counting System—Theapparatusshouldincludea Deployment of a barbed proximal stent into vasculature with a
cycle counting system for measuring the number of loading highangulation,forexample,mayresultinengagementofonly
cycles applied to the test specimen. The cycle counting system thebarbsalongtheoutercurvatureofthevasculatureandcause
should be verified at the test frequencies and the verification a non-uniform, off-axis load distribution. To account for the
should be documented. presence of angulation on AFC and/or attachment mechanism
F3374 − 19
loading, it is acceptable to utilize test fixtures that allow for the 8.2.1 Use of a Mock Vessel—If the test is to be conducted
direct testing of angulated test specimens. When testing angu- using a mock vessel as a constraint or means of loading the test
specimen, the mock vessel should be capable of withstanding
lated test specimens, it is important to consider that the loading
on individual AFCs or attachment mechanisms may differ and the test conditions and maintaining the desired loading
throughout the testing. When AFCs and/or attachment mecha-
that this may affect the number of test specimens needed.
nisms are tested using an endovascular prosthesis and a mock
Alternatively, another method is to determine (e.g., analyti-
vessel,testspecimensshouldbedeployedinthemockvesselin
cally) the loading increase caused by angulation (or other
such a manner so as to ensure the intended load distribution
conditions) and then apply that loading to test specimens in a
amongAFCs and/or attachment mechanisms. Mock vessels for
straight configuration as shown in Appendix X1.
accelerated testing may not need a physiologically relevant
8.1.3 The AFC and/or attachment mechanism should be
radial or longitudinal stiffness, and stiffer or thicker walled
tested to a prescribed load level and direction. The load is
mock vessels may be used to obtain the desired AFC and/or
typically applied in either force or displacement control. The
attachment mechanism loading. Stiffer mock vessels may
area or point and direction of application of the force or
allow for faster test frequencies and reduce the incidence of
displacement should reproduce the appropriate loading on the
mock vessel tears, but may also limit the ability to reliably
AFC and/or attachment mechanism. When testing multiple
control test loads. A mock vessel selection rationale should be
specimens in the same test system, care should be taken to
provided as part of the test system (machine and fixture)
ensure that the desired loading is applied to all specimens.This
justification to demonstrate suitability for active fixation sys-
can be accomplished using individual load cells and/or dis-
tem durability testing. References (14-17) may be helpful in
placement instrumentation.
comparing physiological parameters (e.g., radial or longitudi-
8.1.4 When determining the loading magnitude, consider-
nal stiffness) to those of the mock vessels.
ation should be given to alternating and mean blood pressures.
8.2.1.1 Effect of Oversizing—The mock vessel inner diam-
Although higher mean blood pressures typically lead to higher
eter should be appropriate for the deployed endovascular
forces, lower mean blood pressures could lead to higher
prosthesis’s diameter and should maintain intended geometry
displacements and higher abrasion, depending on the device
(i.e., not drift substantially with time) over the duration of the
design and indications. In some situations, such as when a
test, unless otherwise justified.
worst-case load cannot be clearly identified, it may be appro-
8.2.1.2 Mock Vessel and Active Fixation System Overlap—
priate to evaluate active fixation system durability under more
Unless otherwise justified, the overlap between the mock
than one condition to fully characterize performance.
vessel and the active fixation system should be minimized to
8.1.5 Durability testing of active fixation systems has his-
ensure that the intended loading is applied to the AFCs and/or
torically been conducted with constant amplitude loading even attachment mechanisms and not artifactually reduced by fric-
thoughloadingisknowntobevariableduetochangesinblood
tion effects.
pressure, musculoskeletal motions, and other factors after 8.2.2 Use of a Rigid Contact Test Interface—If the test
implantation. When determining loading conditions, it may be specimen is to be tested by deploying it against a rigid contact
test interface (an example of which is shown in Fig. X1.1), the
appropriate to consider
...